Project Summary/Abstract Type 1 diabetes (T1D) is among the most common chronic conditions of childhood and its management is complex and relentless. Adolescents have increased risk for worsening glycemic control, putting them at risk for short- and long-term complications. As responsibility for daily T1D management tasks begins to shift from parents to youth, supportive parent-adolescent teamwork promotes optimal diabetes outcomes. However, adolescents' cognitive development, desire for autonomy, and changing family and social relationships can make adherence to treatment recommendations difficult and strain attempts at parent-adolescent teamwork. We aim to develop and pilot test a mobile app-based behavioral intervention to facilitate positive, supportive parent-adolescent interactions around T1D management. The proposed study has two parts. First, we plan to involve adolescents with T1D (age 12-17), their parents, and diabetes care providers in designing a smartphone app that supports parents to recognize, keep track of, and reinforce their adolescents for specific positive T1D-related behaviors, or strengths. Example strengths include asking for help with complicated diabetes tasks, talking to friends about diabetes, and expressing confidence or optimism about T1D management. Intermittently throughout the day, the app will push parents a prompt to report which positive T1D behaviors their adolescent has engaged in. The app will generate weekly summary reports of each adolescent's most frequent strength behaviors, and parents will be reminded via the app to praise their adolescent for those patterns. Second, we plan to pilot test this intervention with 82 families; parents will be randomized to an intervention or a control condition. Participants in the intervention condition will use the app for 6 months and provide feedback, and control participants will receive usual care and will not use the app. Our main goal is to determine how often and in what ways families use the app, whether they like it, and to obtain suggestions for improvement. We will also evaluate trends for impact on important diabetes outcomes, such as quality of parent-adolescent relationships, T1D treatment adherence, and glycemic control. Data ? including questionnaires, adherence data from blood glucose meters, and glycemic control biomarkers from a blood draw ? will be collected at baseline and again 3 and 6 months later. The results of this pilot study will help refine the intervention so that it can be evaluated in a full- scale randomized controlled trial. Ultimately, the goal of this research is to validate brief, convenient, and helpful tools that families of all adolescents with T1D can use to strengthen positive family teamwork and ultimately promote optimal diabetes health outcomes.